U.S. patent application number 10/976720 was filed with the patent office on 2006-05-04 for magnetic head and magnetic disk storage apparatus mounting the same.
This patent application is currently assigned to Hitachi Global Storage Technologies Netherlands, B.V.. Invention is credited to Kimitoshi Etoh, Masafumi Mochizuki, Kaori Suzuki.
Application Number | 20060092575 10/976720 |
Document ID | / |
Family ID | 35024703 |
Filed Date | 2006-05-04 |
United States Patent
Application |
20060092575 |
Kind Code |
A1 |
Mochizuki; Masafumi ; et
al. |
May 4, 2006 |
Magnetic head and magnetic disk storage apparatus mounting the
same
Abstract
Embodiments of the invention provide a magnetic head which
assures an improved format efficiency without increase in the
magnetic field intensity applied at a read element. In one
embodiment, a magnetic head incorporates a write head having a main
pole and an auxiliary pole, and a read head having a read element
between reader shields. An auxiliary shield as a magnetic body is
provided between the main pole and reader shields or on the
opposite side of the main pole with the reader shields between the
main pole and the auxiliary shield.
Inventors: |
Mochizuki; Masafumi; (Tokyo,
JP) ; Suzuki; Kaori; (Tokyo, JP) ; Etoh;
Kimitoshi; (Kanagawa, JP) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Hitachi Global Storage Technologies
Netherlands, B.V.
AZ Amsterdam
NL
|
Family ID: |
35024703 |
Appl. No.: |
10/976720 |
Filed: |
October 29, 2004 |
Current U.S.
Class: |
360/317 ;
360/319; G9B/5.044; G9B/5.068; G9B/5.083; G9B/5.089; G9B/5.135 |
Current CPC
Class: |
G11B 5/312 20130101;
G11B 5/3967 20130101; G11B 5/1278 20130101; G11B 5/3143 20130101;
G11B 5/265 20130101 |
Class at
Publication: |
360/317 ;
360/319 |
International
Class: |
G11B 5/33 20060101
G11B005/33; G11B 5/127 20060101 G11B005/127 |
Claims
1. A magnetic head comprising: a read head having a lower shield,
an upper shield, and a magneto resistive element located between
said lower and upper shields; a write head having a main pole and
an auxiliary pole; and an auxiliary shield as a magnetic body
located on a leading side of said main pole.
2. The magnetic head as claimed in claim 1, wherein said main pole
is located between said auxiliary pole and said upper shield, and
said auxiliary shield is located between said main pole and said
upper shield.
3. The magnetic head as claimed in claim 2, wherein a length of
said auxiliary shield in a direction of an element height is longer
than a length of said lower and upper shields in the direction of
the element height.
4. The magnetic head as claimed in claim 2, wherein a length of
said auxiliary shield in a direction of a track width is longer
than a length of said lower and upper shields in the direction of
the track width.
5. The magnetic head as claimed in claim 2, wherein a length of
said auxiliary shield in a direction of an element height is
shorter than a distance from an air bearing surface to a position
farthest from the air bearing surface in an area of connection of
said main pole and said auxiliary pole.
6. The magnetic head as claimed in claim 2, wherein a distance
between said auxiliary shield and said upper shield is about 1
.mu.m or more.
7. The magnetic head as claimed in claim 2, wherein the auxiliary
shield is recessed from an air bearing surface.
8. The magnetic head as claimed in claim 2, wherein the auxiliary
shield is larger in area than the lower shield and the upper
shield.
9. The magnetic head as claimed in claim 1, wherein said main pole
is located between said auxiliary pole and said upper shield and
said auxiliary shield is located on a leading side of said lower
shield.
10. The magnetic head as claimed in claim 9, wherein an upper part
of the auxiliary shield protrudes toward a back contact position
side of the main pole.
11. The magnetic head as claimed in claim 9, wherein a relation of
.mu.1.gtoreq..mu.2 is satisfied where .mu.1 represents permeability
of said auxiliary shield and .mu.2 represents permeability of said
upper and lower shields.
12. The magnetic head as claimed in claim 9, wherein a relation of
L1.ltoreq.L2 is satisfied where L1 represents a distance from a
position farthest from the air bearing surface in an area of
connection of said main pole and said auxiliary pole to the
auxiliary shield and L2 represents a distance from a position
farthest from the air bearing surface in an area of connection of
said main pole and said auxiliary pole to said upper shield.
13. The magnetic head as claimed in claim 9, wherein a relation of
(.mu.1/L1).gtoreq.(.mu.2/L2) is satisfied where .mu.1 represents
permeability of said auxiliary shield, .mu.2 represents
permeability of said upper shield, L1 represents a distance from a
position farthest from an air bearing surface in an area of
connection of said main pole and said auxiliary pole to the
auxiliary shield, and L2 represents a distance from a position
farthest from the air bearing surface in an area of connection of
said main pole and said auxiliary pole to said upper shield.
14. The magnetic head as claimed in claim 9, wherein a length of
said auxiliary shield in a direction of a track width is longer
than a length of said lower and upper shields in the direction of
the track width.
15. The magnetic head as claimed in claim 9, wherein a distance
between said auxiliary shield and said lower shield is about 1
.mu.m or more.
16. A magnetic disk storage apparatus comprising: a magnetic
recording medium having a magnetic recording layer and a soft
underlayer; a medium drive which drives said magnetic recording
medium; a magnetic head which writes to, and reads from, said
magnetic recording medium; and a magnetic head drive which drives
said magnetic head with respect to said magnetic recording medium,
wherein said magnetic head comprises a read head having a lower
shield, an upper shield and a magneto resistive element located
between said upper and lower shields; a write head having a main
pole and an auxiliary pole; and an auxiliary shield as a magnetic
body which is located on a leading side of said main pole.
17. A method of manufacturing a magnetic head which includes a read
head having a lower shield, an upper shield and a magneto resistive
element located between said upper and lower shields; a write head
having a main pole and an auxiliary pole; and an auxiliary shield
which is located on a leading side of said main pole, said method
comprising: making said read head; forming an inorganic insulating
layer thereover; forming, over said inorganic insulating layer, a
magnetic layer which is to constitute said auxiliary shield;
forming an inorganic insulating layer over said magnetic layer; and
forming said write head thereover.
18. A method of manufacturing a magnetic head which includes a read
head having a lower shield, an upper shield and a magneto resistive
element located between said upper and lower shields; a write head
having a main pole and an auxiliary pole; and an auxiliary shield
which is located on a leading side of said main pole, said method
comprising: forming an inorganic insulating layer on a substrate;
forming, over said inorganic insulating layer, a magnetic layer
which is to constitute said auxiliary shield; forming an inorganic
insulating layer thereover; making said read head thereover;
forming an inorganic insulating layer thereover; and forming said
write head thereover.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims priority from Japanese Patent
Application No. 2004-050342, filed Feb. 25, 2004, the entire
disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a perpendicular recording
magnetic head, a manufacturing method thereof, and a magnetic disk
storage apparatus which incorporates the same.
[0003] A magnetic disk storage apparatus incorporates a magnetic
recording medium and a magnetic head, and data on the recording
medium is read or written by the magnetic head. In order to
increase the capacity of the magnetic disk storage, the areal
density has to be increased. However, in the conventional
longitudinal recording method, the thermal fluctuation in medium
magnetization prevents one from achieving the higher areal density.
A solution to this problem is a perpendicular recording method
whereby the recorded magnetizations are aligned in the direction
perpendicular to the medium.
[0004] The perpendicular recording method is available in two
types: one type uses a double-layered perpendicular medium having a
soft underlayer and the other type uses a single-layered
perpendicular medium having no soft underlayer. When a
double-layered perpendicular medium is used as a recording medium,
it is necessary to use a single-pole type head which has a main
pole and an auxiliary pole for recording. In this case, a higher
magnetic field intensity can be applied to the medium. Taking into
consideration that the head may have a skew angle, it is desirable
that the shape of the main pole is trapezoidal that the width of
the leading side is smaller than that of the trailing side. FIG. 2
schematically shows the structure of a conventional magnetic head
including a single-pole type head. As shown in FIG. 2, a
conventional magnetic head includes a lower shield 8, a read
element 7, an upper shield 9, an auxiliary pole 3, a thin film
conductor coil 2, and a main pole 1 which are laminated in the
downtrack direction (from the leading side) in the order of
mention. The lower shield 8, read element 7 and upper shield 9
constitute a read head 24 while the auxiliary pole 3, thin film
conductor coil 2 and main pole 1 constitute a write head
(single-pole type head) 25. Japanese Patent Laid Open Publication
No. 2003-45008 describes a single-pole type head in which a shield
for an external magnetic field is located with a gap film between
the main pole and shield in a way to be recessed from the surface
opposite to the medium.
BRIEF SUMMARY OF THE INVENTION
[0005] The present invention relates to a perpendicular recording
system which uses a perpendicular recording write head with a main
pole and an auxiliary pole and a double-layered perpendicular
recording medium with a soft underlayer. As shown in FIG. 2, since
the conventional magnetic head has the auxiliary pole and the thin
film coil between the read element and the main pole, the
write-read element distance is large which causes a degradation of
the format efficiency. A structure as shown in FIG. 3 has been
proposed to avoid this problem, where the auxiliary pole is located
on the trailing side of the main pole. This structure can decrease
the write-read element distance.
[0006] Not only the write field intensity of the write head but
also write-field gradients which determine the magnetization
transitions are important factors for achieving a high recording
density. In order to achieve a higher recording density, the
write-field gradients must be increased. An approach to increasing
the write-field gradients is a structure in which a magnetic body
32 is located on the trailing side of the main pole 1. Even in this
structure, it is desirable that the auxiliary pole 3 is located on
the trailing side of the main pole 1 as shown in FIG. 3, in order
to make up a closed magnetic path.
[0007] However, in the structure shown in FIG. 3 where the main
pole 1 is located on the leading side of the auxiliary pole 3, the
magnetic field intensity applied at the read element 7 is higher
than in the conventional magnetic head structure shown in FIG. 2.
The reason for this is that as the main pole 1 and the read element
7 are closer to each other, the auxiliary pole 3 no longer exists
between the lower shield and the upper shield (hereinafter these
are sometimes called the "reader shields"). According to the
three-dimensional magnetic field calculation made by the inventors,
the magnetic field intensity applied at the read element in the
conventional structure shown in FIG. 2 is 1.18.times.104 A/m while
that in the structure shown in FIG. 3 is 4.40.times.104 A/m. This
increase in magnetic field intensity, however, might cause an
instability in reading characteristics or damage to the read
element 7, making it difficult to achieve a high recording density
in a magnetic disk storage apparatus.
[0008] Also, in Japanese Patent Laid Open Publication No.
2003-45008, the field intensity applied at the read element is not
taken into consideration.
[0009] One feature of the present invention is to provide a
magnetic head which assures an improved format efficiency without
increase in the magnetic field intensity applied at the read
element and also provide a magnetic disk storage apparatus which
uses the head to achieve a high recording density.
[0010] According to an aspect of the present invention, a magnetic
head includes a read head having a lower shield, an upper shield,
and a magneto resistive element located between the upper and lower
shields; and a write head having a main pole and an auxiliary pole.
The magnetic head further includes an auxiliary shield as a
magnetic body which is located on the leading side of the main
pole. The main pole is located between the auxiliary pole and the
upper shield. The auxiliary shield is located between the main pole
and the upper shield or on the leading side of the lower shield so
that leakage magnetic flux from the write head, particularly
leakage magnetic field from the vicinity of the position of back
contact in the area of connection of the main pole and auxiliary
pole, is absorbed and the magnetic field intensity applied at the
read element is reduced.
[0011] According to a feature of the present invention, the
magnetic field intensity applied at the read element is reduced and
the main pole of the write head is located closer to the read
element to improve the format efficiency without deterioration in
the read element or damage to it.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic cross-section view showing a magnetic
head according to an embodiment of the present invention.
[0013] FIG. 2 shows the structure of a conventional magnetic
head.
[0014] FIG. 3 shows a magnetic head in which an auxiliary pole is
on the trailing side of the main pole.
[0015] FIG. 4 is a schematic diagram showing a magnetic disk
storage apparatus.
[0016] FIG. 5 is a schematic diagram illustrating how perpendicular
recording is done.
[0017] FIG. 6 is a schematic cross-section view showing a magnetic
head according to another embodiment of the present invention.
[0018] FIG. 7 is a schematic cross-section view showing a magnetic
head according to another embodiment of the present invention.
[0019] FIG. 8 is a schematic cross-section view showing a magnetic
head according to another embodiment of the present invention.
[0020] FIG. 9 is a schematic plan view showing a magnetic head
according to an embodiment of the present invention, as viewed from
the reader shields.
[0021] FIG. 10 is a schematic cross-section view showing a magnetic
head according to a further embodiment of the present
invention.
[0022] FIG. 11 shows the relation between the magnetic field
intensity applied at the read element and the distance between the
read element and the main pole, L.sub.RW.
[0023] FIG. 12 is a schematic cross-section view showing a magnetic
head according to another embodiment of the present invention.
[0024] FIG. 13 is a set of cross-section views showing the process
of manufacturing a magnetic head according to an embodiment of the
present invention.
[0025] FIG. 14 is a set of cross-section views showing the process
of manufacturing a magnetic head according to another embodiment of
the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Specific embodiments of the present invention will be
described referring to the accompanying drawings. In the drawings,
elements with like functions are designated by like reference
numerals to help reader understanding.
[0027] FIG. 4 is a conceptual diagram showing a magnetic disk
storage apparatus according to an exemplary embodiment of the
present invention. In this magnetic disk storage apparatus, a
magnetic head mounted on a slider 13 fixed to the tip of a
suspension arm 12 writes and reads magnetization signals at a given
position on a magnetic disk (magnetic recording medium) 11 which is
rotated by a motor 28. A rotary actuator 15 is driven to select a
magnetic head position (track) in the magnetic disk radial
direction. A write signal to the magnetic head and a read signal
from it are processed by signal processing circuits 35a and
35b.
[0028] FIG. 1 is a schematic cross-section view showing a magnetic
head according to an embodiment of the present invention. This
magnetic head is a write/read combination head which has a write
head 25 with a main pole 1 and an auxiliary pole 3, and a read head
24 with a read element 7. The main pole 1 and the auxiliary pole 3
are magnetically connected in a position away from the air bearing
surface through a pillar 17 and a thin film coil 2 is interlinked
with a magnetic circuit which is composed of the main pole 1,
auxiliary pole 3, and pillar 17. The read element 7, which is a
giant magneto resistive element (GMR) or a tunneling magneto
resistive element (TMR), is located between a pair of magnetic
shields (reader shields): a lower shield 8 (leading side) and an
upper shield 9 (trailing side). The main pole 1 is located on the
leading side of the auxiliary pole 3. A magnetic body 32 for
increasing magnetic field gradients is located on the trailing side
of the main pole 1.
[0029] As mentioned earlier, when the main pole 1 is located on the
leading side of the auxiliary pole 3, the problem that the magnetic
field intensity applied at the read element 7 is increased arises.
Therefore, according to this embodiment of the present invention,
an auxiliary shield 30 as a magnetic body is provided on the
leading side of the main pole 1, or in the case shown in FIG. 1,
between the main pole 1 and the upper shield 9 of the read head 24.
This structure decreases the magnetic flux flowing from the main
pole 1 to the lower and upper shields 8 and 9 and reduces the
magnetic field intensity applied at the read element 7.
[0030] According to the three-dimensional magnetic field
calculation made by the inventors, the magnetic field intensity
applied at the read element in the structure shown in FIG. 3 is
4.40.times.10.sup.4 A/m. This increase in the magnetic field
intensity applied at the read element might cause deterioration in
reading characteristics or damage to the read element. This
three-dimensional magnetic field intensity calculation assumes that
the saturation flux density of the main pole is 2.4 T, the
geometric width is 120 nm, and the thickness is 150 nm. Also it is
assumed that the saturation flux density of the auxiliary pole 3
and reader shields 8 and 9 is 1.0 T, and the distance between the
main pole and the upper shield is 5 .mu.m. On the other head, in
the magnetic head according to the present embodiment as shown in
FIG. 1, when the distance between the main pole and the upper
shield is 5 .mu.m and that between the main pole 1 and the
auxiliary shield 30 is 2 .mu.m, the magnetic field intensity
applied at the read element is remarkably low at
8.11.times.10.sup.3 A/m. Here, the thickness of the auxiliary
shield 30 is 2 .mu.m and its length is 20 .mu.m. The saturation
flux density of the auxiliary shield 30 is assumed to be 1.0 T.
[0031] When the head has an auxiliary shield 30 as shown in FIG. 1,
write-field gradients can be sharp without deterioration in reading
characteristics. The use of the auxiliary shield 30 increases
resistance to the influence of an external magnetic field. The
influence of an external magnetic field here refers to a problem
that the main pole might be excited by a magnetic field which is
stray in the magnetic disk storage apparatus, namely a magnetic
field generated by a factor other than write current. For example,
what is called an "external magnetic field" and consequently a
leakage magnetic field from the main pole might erase written
signals on the medium. However, according to the present
embodiment, the auxiliary shield absorbs an external magnetic
field, which reduces the intensity of the magnetic field from the
main pole, thereby preventing the problem that written signals on
the medium might be erased.
[0032] It is desirable that the distance between the auxiliary
shield 30 and the upper shield 9 is about 1 .mu.m or more. When the
distance between the auxiliary shield 30 and upper shield 9 should
be insufficient, much magnetic flux would flow from the auxiliary
shield 30 to the upper shield 9 and consequently the magnetic field
intensity applied at the read element 7 would increase. According
to the inventors' calculation, when the distance between the
auxiliary shield 30 and the upper shield 9 is 0.1 .mu.m, the
magnetic field intensity applied at the read element 7 is 1.5 times
more than when it is 1 .mu.m.
[0033] FIG. 5 shows the relation between the perpendicular
recording magnetic head 14 and the magnetic disk 11 and outlines
how perpendicular recording is done. A magnetic field from the main
pole 1 of the write head 25 passes through a recording layer 19 and
a soft underlayer 20 of the magnetic disk medium 11 and enters the
auxiliary pole 3 to make up a magnetic circuit so that a
magnetization pattern is recorded on the recording layer 19. There
may be an intermediate layer between the recording layer 19 and the
soft underlayer 20. The read element 7 of the read head 24 may be a
giant magneto resistive element (GMR) or a tunneling magneto
resistive element (TMR).
[0034] FIG. 6 is a schematic cross-section view showing a magnetic
head according to another embodiment of the present invention. In
this magnetic head, the auxiliary shield 30 is recessed from the
air bearing surface. This structure reduces the magnetic field
intensity applied from the auxiliary shield 30 to the recording
medium. When the recession of the auxiliary shield 30 is larger,
the resistance of the magnetic path from the auxiliary shield 30 to
the soft underlayer of the magnetic recording medium is larger,
which may make it impossible to reduce the magnetic field intensity
applied at the read element. Hence, preferably the recession of the
auxiliary shield 30 from the air bearing surface should be about 1
.mu.m or less.
[0035] FIG. 7 is a schematic cross-section view showing a magnetic
head according to another embodiment of the present invention.
Regarding the relation between the length of the auxiliary shield
30 in the direction of the element height, L.sub.AS, and the length
of the reader shields 8 and 9 in the direction of the element
height, L.sub.S, it is desirable that the length of the auxiliary
shield 30 is longer than the length of the reader shields 8 and 9
as illustrated in FIG. 7 so that magnetic flux does not flow from
the vicinity of the position of back contact into the reader
shields 8 and 9 while writing operation is under way. Another
approach is that as illustrated in the figure, L.sub.s, the length
of the reader shields 8 and 9 in the direction of the element
height is shorter than L.sub.BK, the length from the air bearing
surface to the position of back contact (position farthest from the
air bearing surface in the area of connection of the main pole and
auxiliary pole). In addition, it is desirable that the width of the
auxiliary shield 30 in the direction of the track width is larger
than the width of the reader shields 8 and 9 in the direction of
the track width.
[0036] FIG. 8 is a schematic cross-section view showing a magnetic
head according to another embodiment of the present invention. As
illustrated in FIG. 8, it is desirable that L.sub.AS, the length of
the auxiliary shield 30 in the direction of the element height is
shorter than L.sub.BK, the length of the main pole 1 from the air
bearing surface to the position of back contact, and longer than
L.sub.S, the length of the reader shields 8 and 9 in the direction
of the element height. The reason for this is that this structure
reduces the magnetic field intensity applied at the read element
and at the same time decreases the magnetic flux flowing into the
auxiliary shield 30 and reduces the leakage magnetic field from the
auxiliary shield 30 to the medium.
[0037] FIG. 9 is a schematic plan view showing a magnetic head
according to an embodiment of the present invention, as viewed from
the reader shields. It is desirable that the area of the auxiliary
shield 30 is larger than that of the lower shield 8 and the upper
shield 9. Also, it is desirable that the width of the auxiliary
shield 30 in the direction of the track width is larger than that
of the lower shield 8 and the upper shield 9. Owing to this
structure, more magnetic flux is absorbed by the auxiliary shield
30 and the magnetic flux which flows from the main pole 1 into the
lower and upper shields 8 and 9 decreases, resulting in reduction
in the magnetic field intensity applied at the read element 7. By
contrast, when the area of the auxiliary shield 30 should be
smaller than the area of the lower and upper shields 8 and 9 or the
width of the auxiliary shield 30 in the direction of the track
width should be smaller than the width of the lower and upper
shields 8 and 9 in the direction of the track width, undesirably no
magnetic body as a shield would exist between the reader shields 8
and 9 and the position of back contact of the main pole 1.
[0038] FIG. 10 is a schematic cross-section view showing a magnetic
head according to a further embodiment of the present invention. In
the magnetic head according to this embodiment, the auxiliary
shield 30 is located on the leading side of the main pole 1, unlike
the above embodiments where it is between the main pole 1 and the
reader shields 8 and 9, in a way that the reader shields 8 and 9
are between the main pole 1 and the auxiliary shield 30.
Specifically, the auxiliary shield 30 is located between a
substrate of alumina titanium carbide or glass and the reader
shields 8 and 9. In this embodiment, the thickness of the auxiliary
shield 30 is about 2 .mu.m and its length is about 20 .mu.m. The
saturation flux density is assumed to be 1.0 T. This arrangement is
also effective in reducing the magnetic field intensity applied at
the read element.
[0039] FIG. 11 shows comparison between the conventional head
structure (FIG. 3) and the present embodiment's head structure
(FIG. 10) in the relation between the magnetic field intensity
applied at the read element and the distance L.sub.RW from the main
pole trailing end to the read element. In both the structures, the
height of the reader shields is 5 .mu.m, or shorter than the
position of back contact. The only difference between the two
structures is that one has an auxiliary shield and the other does
not. In either structure, as L.sub.RW, the distance from the main
pole 1 to the read element 7 increases, the magnetic field
intensity applied at the read element 7 decreases. However, when
they are equal in distance L.sub.RW, the magnetic field intensity
applied at the read element 7 in the present embodiment's structure
(FIG. 10) is about 60% of that in the conventional structure (FIG.
3). Therefore, the present embodiment (FIG. 10) makes it possible
that L.sub.RW, the distance from the main pole 1 to the read
element 7, may be shorter while the magnetic field intensity
applied at the read element 7 is the same as in the conventional
structure. This means that the apparatus's format efficiency can be
improved. When the reader shields 8 and 9 are between the main pole
1 and the auxiliary shield 30 (FIG. 10), because of the absence of
a magnetic body between the main pole and the reader shields, the
distance between the main pole 1 and the read element 7 may be
shorter than in the structure in which the auxiliary shield 30 is
located between the main pole 1 and the reader shields 8 and 9
(FIG. 1).
[0040] In the structure shown in FIG. 10 in which the reader
shields 8 and 9 are between the main pole 1 and the auxiliary
shield 30, it is desirable that the direct distance from the
position of back contact of the main pole 1 to the auxiliary shield
30, L1, is smaller than the direct distance from the position of
back contact of the main pole to the reader shields, L2. In the
reverse case, i.e., when L1 should be larger than L2, magnetic flux
from the position of back contact of the main pole 1 would more
easily flow from the auxiliary shield 30 to the lower and upper
shields 8 and 9 and the effect of the auxiliary shield 30 would
become smaller.
[0041] It is desirable that the permeability of the auxiliary
shield material (.mu.1) is higher than that of the reader shield
material (.mu.2). More preferably, .mu.1/L1 should be larger than
.mu.2/L2. This makes it easier for magnetic flux from the position
of back contact of the main pole 1 to flow to the auxiliary shield
30 and improves the effect of reduction in the magnetic field
intensity applied at the read element. In the reverse case, namely
when .mu.1/L1 should be smaller than .mu.2/L2, magnetic flux from
the position of back contact of the main pole 1 would more easily
flow from the auxiliary shield 30 to the lower and upper shields 8
and 9 and lowers the effect of the auxiliary shield.
[0042] It is also desirable that the distance between the auxiliary
shield 30 and the lower shield 8 is about 1 .mu.m or more. When
this distance should be small, more magnetic flux would flow from
the auxiliary shield 30 to the lower shield 8 and undesirably the
magnetic field intensity applied at the read element 7 would be
higher.
[0043] When the reader shields 8 and 9 are between the main pole 1
and the auxiliary shield 30, an upper part of the auxiliary shield
30 may protrude toward the back contact position side of the main
pole 1 as illustrated in FIG. 12. This also makes it easier for the
magnetic flux from the position of back contact of the main pole 1
to flow to the auxiliary shield 30, resulting in improvement in the
effect of reduction in the magnetic field intensity applied at the
read element. It is desirable that the length of the auxiliary
shield 30 in the direction of the element height is longer than the
length of the reader shields in the direction of the element height
and that the width of the auxiliary shield 30 in the direction of
the track width is larger than the width of the reader shields.
[0044] Next, a magnetic head manufacturing method according to an
embodiment of the present invention will be described. FIG. 13
consists of cross-section views illustrating the steps of
manufacturing a magnetic head in which an auxiliary shield as a
magnetic body is between a main pole and an upper shield of a read
head.
[0045] At step (a), an inorganic insulating layer 101 is formed on
a substrate 103 of alumina titanium carbide, glass or the like. A
magnetic layer 102 which is to constitute a lower shield is formed
on the flat inorganic insulating layer 101 by flame coating. The
length of the magnetic layer 102 should be shorter than the length
up to the position of back contact which will be later determined.
At step (b), an inorganic insulating layer 101 which is to
constitute a lower gap is formed thereover by sputtering and
flattened by a chemical mechanical polish (CMP) process. Then, a
read element 7 and an electrode layer and a bias layer for
electrifying it are formed thereover. At step (c), an inorganic
insulating layer 101 which is to constitute an upper gap layer is
formed by sputtering in a way to cover the read element 7,
electrode layer, and bias layer. At step (d), a magnetic layer 102'
which is to constitute an upper shield is formed by flame coating.
The length of the magnetic layer 102' should be shorter than the
length of an auxiliary shield and the length up to the position of
back contact which will be later determined.
[0046] After this, at step (e), an inorganic insulating layer 101
is formed and at step (f), a magnetic layer 102'' which is to
constitute an auxiliary shield is formed by flame coating. Then, at
step (g), an inorganic insulating layer 101 is formed and at step
(h), procedures of making a main pole, a magnetic body on the
trailing side of the main pole, coils, an auxiliary pole and the
like sequentially are taken to obtain a magnetic head according to
the embodiments of the present invention.
[0047] FIG. 14 consists of cross-section views illustrating the
steps of manufacturing a magnetic head in which the reader shields
are between the main pole and the auxiliary shield.
[0048] At step (a), an inorganic insulating layer 104 is formed on
a substrate 103 of alumina titanium carbide, glass or the like. A
magnetic layer 105 which is to constitute an auxiliary shield is
formed on the flat inorganic insulating layer 104 by flame coating.
At step (b), an inorganic insulating layer 101 is formed thereover
and then a magnetic layer 102 which is to constitute a lower shield
is formed by flame coating. The length of the magnetic layer 102
should be shorter than the length up to the position of back
contact which will be later determined. At step (c), an inorganic
insulating layer 101 which is to constitute a lower gap is formed
thereover by sputtering and flattened by a chemical mechanical
polish (CMP) process. Then, a read element 7 and an electrode layer
and a bias layer for electrifying it are formed thereover. At step
(d), an inorganic insulating layer 101 which is to constitute an
upper gap layer is formed by sputtering in a way to cover the read
element 7, electrode layer and bias layer. At step (e), a magnetic
layer 102' which is to constitute an upper shield is formed by
flame coating. The length of the magnetic layer 102' should be
shorter than the length up to the position of back contact which
will be later determined. After this, at step (f), an inorganic
insulating layer 101 is formed and at step (g), procedures of
making a main pole, a magnetic body on the trailing side of the
main pole, coils, an auxiliary pole and the like are sequentially
taken to obtain a magnetic head according to the embodiments of the
present invention.
[0049] It is to be understood that the above description is
intended to be illustrative and not restrictive. Many embodiments
will be apparent to those of skill in the art upon reviewing the
above description. The scope of the invention should, therefore, be
determined not with reference to the above description, but instead
should be determined with reference to the appended claims along
with their full scope of equivalents.
* * * * *